1. Field of the Invention
The present invention relates to a twin-shaft gas turbine and more particularly to a twin-shaft gas turbine that is suitable to be used in common for 50 Hz and 60 Hz for power generation.
2. Description of the Related Art
In general, a twin-shaft gas turbine has a gas generator and a low-pressure turbine. The gas generator includes a compressor, a burner and a high-pressure turbine. The low-pressure turbine is connected to a load (power turbine). The rotating shaft (gas generator shaft) of the gas generator is separate from the rotating shaft of the low-pressure turbine (refer to, for example, JP-2010-25069-A). In the gas generator, the compressor generates compressed air and the burner burns a fuel mixed with the compressed air received from the compressor to generate combustion gas. The combustion gas generated by the burner rotationally drives the high-pressure turbine to generate driving force for the compressor. The combustion gas is then supplied to the low-pressure turbine and rotationally drives the same.
For such a twin-shaft gas turbine generally using a reducer, either of a 60 Hz power generator and a 50 Hz power generator can be driven by changing the reducer depending on the power generator. In contrast, with those directly combining a gas turbine with a power generator without using a reducer, different gas turbines are used for driving a 50 Hz power generator and a 60 power generator.